A number of forgery-prevention measures have long been tried for cards like credit cards and cash cards as well as items that need authentication and forgery prevention, such as tradable coupons, IDs and valuable papers. For instance, a credit card has been provided on its surface with a rainbow hologram composed of a relief hologram having a metal reflective layer for visual authentication. However, the relief hologram has been susceptible of forgery because of easy access to material, established mass copying technologies, and so on, often resulting in difficulty in authentication.
With this in mind, a Lippmann hologram is now used as a hologram distinguishable from the relief hologram. Typically, Patent Publication 1 discloses that if a Lippmann hologram with information added to it is fabricated, it becomes easy to tell it from its counterfeit.